Gram-negative bacilli

Question 1

What are the identifiable features of P. aeruginosa?

Answer 1

Oxidase positive, gram negative rod/bacilli

Produces green pigment

Question 1

What is P. aeruginosa commonly associated with?

Answer 1

1. Opportunistic infections - major cause of nosocomial infections
2. Contact lens keratitis

Question 2

What are some of the common nosocomial infections caused by P. aeruginosa?

Answer 2

1. Pneumonia
2. UTI
3. SSTIs

All may progress to bacteraemia/septicaemia

Question 3

What are some common community-acquired infections caused by P. aeruginosa?

Answer 3

1. Malignant otitis externa - especially in elderly diabetic patients
2. Contact lens keratits
3. Nail infection

Question 4

How is B. pseudomallei identifiable?

Answer 4

Gram-negative bacilli, grows as wrinkled colonies

Question 5

What gram-negative bacilli infection is notifiable to MOH?

Answer 5

Burkholderia pseudomallei & V. cholerae infection

Question 6

What does B. pseudomallei infection cause?

Answer 6

Melioidosis

Question 7

What is the most common environmental source of B. pseudomallei infections?

Answer 7

Surface soil or water

Question 8

What are the common clinical presentations of melioidosis?

Answer 8

1. Septicaemia
2. Pneumonia
3. Chronic infection
4. Abscesses

Question 9

What are the groups at risk for melioidosis?

Answer 9

1. Immuno-compromised - e.g. diabetics, 40-70% of patients have DM
2. Occupations with exposure to soil and water

Question 9

Is B. pseudomallei intracellular or extracellular?

Answer 9

Intracellular

Question 10

How is melioidosis diagnosed?

Answer 10

Blood culture or serology

Question 11

What are the 2 countries associated with B. pseudomallei infections?

Answer 11

North Australia and North-Eastern Thailand

Question 12

What group of people is B. cepacia infamous for infecting?

Answer 12

Patients with cystic fibrosis

Question 13

What is the main virulence factor of V. cholerae?

Answer 13

Cholera toxin

Question 14

How are the Vibrio spp. transmitted?

Answer 14

Water & raw seafood

Question 15

Which Vibrio spp. is associated with SSTIs, fascitis & septicaemia?

Answer 15

V. vulnificus

Question 16

Which V. cholerae strain carries the cholera toxin?

Answer 16

Type O1 & Type O139

Question 17

What is the hallmark of cholera?

Answer 17

Ricewater stool; copious watery painless diarrhoea

Question 18

What is the main virulence factor of H. influenzae?

Answer 18

Antigenically distinct polysaccharide capsule

Question 19

Why is H. influenzae ‘fussy’?

Answer 19

Dependent on both X and V

Question 20

What are the invasive infections caused by H. influenzae type b?

Answer 20

1. Meningitis
2. Acute epiglottitis
3. Septicaemia
4. Pneumonia
5. Osteomyelitis, septic arthritis
6. Cellulitis

Question 21

How is H. influenzae prevented around the world?

Answer 21

Hib conjugated vaccine

Question 22

What agar is used to grow H. influenzae?

Answer 22

Chocolate agar

Question 23

What antibiotic should be given for severe **H. influenzae** infections?

Answer 23

Ceftriaxone (preferred) / Co-amoxiclav Some H. influenzae strains produce beta lactamases and hence it is safer to give ceftriaxone from the beginning to minimise unresponsiveness to treatment due to AMR

Question 24

What antibiotic should be given for mild URTI infections caused by H. influenzae in the community?

Answer 24

Amoxicillin

Question 25

What disease is the **HACEK group** comonly associated with?

Answer 25

Endocarditis

Question 26

What disease does **B. pertussis** cause?

Answer 26

Pertussis or whooping cough

Question 27

How is pertussis diagnosed?

Answer 27

PCR

Question 28

How is pertussis prevented?

Answer 28

DT**aP** vaccine for children and pregnant women

Question 29

What is the history to take note of from a patient with Brucellosis?

Answer 29

1. PUO 2. Travel history to Middle East 3. Drinking unpasteurized milk

Question 30

Which microbial infection is caused by cat scratches and lice?

Answer 30

Bartonella spp.

Question 31

What microbe is associated with animal bites (including cats & dogs)?

Answer 31

Pasteurella multocida

Question 32

Which microbial spp. causes the plague?

Answer 32

Yersinia spp.

Question 33

What is **Legionella** commonly associated with?

Answer 33

Water & aircon units

Question 34

What are the clinical presentations of a **Legionella** infection?

Answer 34

1. Pneumonia 2. Pontiac fever

Question 35

How is **Legionella** infection diagnosed?

Answer 35

1. Urine antigen test 2. Broncho-Alveolar Lavage culture -> immunofluorescent stain -> NAT

Question 36

What microscopic finding supports the diagnosis of **Bacillary vaginosis**?

Answer 36

Clue cells

Question 37

What infection is typically caused by **Acinetobacter spp.** and who are the at-risk groups?

Answer 37

Causes nosocomial pneumonia Typically affects the immuno-compromised (ICU, burn patients)

Question 38

Treatment for melioidosis?

Answer 38

Ceftazidime or imipenem; 2 week IV 6 months oral maintenance

Question 39

Identifiable features of V. cholerae?

Answer 39

Curved GNR, yellow on TCBS ## Footnote Thiosulphate Citrate Bile Salts & Sucrose

Question 40

Which bacteria grows 'wrinkled' colonies?

Answer 40

Burkholderia pseudomallei

Question 41

Which bacteria grows 'mercury droplet' colonies?

Answer 41

Bordetella pertussis

Question 42

What are the 2 criteria used to diagnose bacillary vaginosis?

Answer 42

1. Amsel criteria 2. Nugent criteria